Hi guys , as you can see in the pic, this is a very important pawn structure as black to play solid chess. This pawn structure can be after e4 d6 (modern philidor) or from d4 d6 and you play this formation as defense from e4 or d4 or c4 or everything. 

2 plans now, blockade the center with c5 and we have either b5 plan or nh5 g6 ng7 f5. 

So keep in mind these preliminary and i will come back with games and more ideas at these 2 plans. The first 10 lessons about will be about this pawn structure and you can see how easily you can be improved by just follow me